cc65/test/val/bitfield.c

/*
  !!DESCRIPTION!! Tests of bit-field packing
  !!ORIGIN!!      cc65 regression tests
  !!LICENCE!!     zlib
  !!AUTHOR!!      Jesse Rosenstock
*/

/*
  see https://github.com/cc65/cc65/issues/1054
*/

#include <stdio.h>

static unsigned char failures = 0;

static struct four_bits {
    unsigned int x : 4;
} fb = {1};

static void test_four_bits(void)
{
    if (sizeof(struct four_bits) != 1) {
        fprintf(stderr, "Got sizeof(struct four_bits) = %zu, expected 1.\n",
                sizeof(struct four_bits));
        failures++;
    }

    if (fb.x != 1) {
        fprintf(stderr, "Got fb.x = %u, expected 1.\n", fb.x);
        failures++;
    }

    fb.x = 3;

    if (fb.x != 3) {
        fprintf(stderr, "Got fb.x = %u, expected 3.\n", fb.x);
        failures++;
    }
}

static struct four_bits_with_int {
    unsigned int x : 4;
    unsigned int y;
} fbi = {1, 2};

static void test_four_bits_with_int(void)
{
    /* We would like this to be 3.  https://github.com/cc65/cc65/issues/1054 */
    if (sizeof(struct four_bits_with_int) != 4) {
        fprintf(stderr,
                "Got sizeof(struct four_bits_with_int) = %zu, expected 4.\n",
                sizeof(struct four_bits_with_int));
        failures++;
    }

    if (fbi.x != 1) {
        fprintf(stderr, "Got fbi.x = %u, expected 1.\n", fbi.x);
        failures++;
    }

    if (fbi.y != 2) {
        fprintf(stderr, "Got fbi.y = %u, expected 2.\n", fbi.y);
        failures++;
    }

    fbi.x = 3;
    fbi.y = 17;

    if (fbi.x != 3) {
        fprintf(stderr, "Got fbi.x = %u, expected 3.\n", fbi.x);
        failures++;
    }

    if (fbi.y != 17) {
        fprintf(stderr, "Got fbi.y = %u, expected 17.\n", fbi.y);
        failures++;
    }
}

static struct overlap {
    unsigned int x : 10;
    unsigned int y : 10;
} o = {11, 22};

/* Tests that bit-fields can share allocation units. */
static void test_overlap(void)
{
    if (sizeof(struct overlap) != 3) {
        fprintf(stderr, "Got sizeof(struct overlap) = %zu, expected 3.\n",
                sizeof(struct overlap));
        failures++;
    }

    if (o.x != 11) {
        fprintf(stderr, "Got o.x = %u, expected 11.\n", o.x);
        failures++;
    }

    if (o.y != 22) {
        fprintf(stderr, "Got o.y = %u, expected 22.\n", o.y);
        failures++;
    }

    o.x = 33;
    o.y = 44;

    if (o.x != 33) {
        fprintf(stderr, "Got o.x = %u, expected 33.\n", o.x);
        failures++;
    }

    if (o.y != 44) {
        fprintf(stderr, "Got o.y = %u, expected 44.\n", o.y);
        failures++;
    }
}

int main(void)
{
    test_four_bits();
    test_four_bits_with_int();
    test_overlap();
    return failures;
}